The present invention relates to an arrangement for driving cabs for vehicles of the kind indicated in the preamble to patent claim 1.
A known practice is to arrange springs, e.g. gas springs or coil springs, between the cab and frame of freight vehicles for the sake of greater comfort while the vehicle is in motion. The springs enable the cab to move between upper and lower endstops which limit cab movement relative to the frame not only during operation but also when the cab is tilted forward to render the engine, situated under the cab, accessible for servicing or repair. In cases where gas springs are used, the endstops are incorporated in the respective springs, which makes the springs expensive and complicated. As powerful forces act upon the endstops, particularly when the cab is tilted, strong spring mountings are also required for fastening the gas springs to the cab. The use of coil springs usually entails the use of a separate shock absorber associated with each spring, in which case the endstops are built into the shock absorber. Like gas springs, shock absorbers are complicated and require strong mountings capable of absorbing the large forces which occur in the spring arrangement during operation and upon tilting.
The object of the present invention is to provide a solution which has the effect of eliminating the disadvantages mentioned above. This is achieved by the features of the invention which includes the cab being supporting by spring elements relative to the vehicle frame. At least one arm and usually two arms extend between the frame and the cab, following the springing movement of the vehicle cab. There are upper and lower stop surfaces at the frame which limit the springing movement of the cab. One end of the link arm is rotatably arranged relative to a supporting element fastened to the frame. The other end of the link arm is arranged in a resilient bushing, preferably a rubber bushing in the carrier element. The link arm is provided with a movement limiter which extends transverse to the longitudinal direction of the vehicle. The movement limiter extends between the top and bottom stop surfaces so that contact between the movement limiter and the stop surfaces which occurs upon movement of the link arm controls the extent of movement of the link arm and controls the tilting movement of the cab. The stop surfaces may be defined in an aperture extending through a carrier secured to the cab. There may be a stabilizer between the cab and the frame and the link arm may be a side piece of that stabilizer. Shock absorbing material may be provided on the movement limiter to damp the shocks when they move the limiter to contact the stop surfaces.
Applying the invention makes it possible to use a simpler gas spring or shock absorber without built-in endstops. It also makes it possible to use significantly less strong mountings, because the endstops being separate from the gas spring or shock absorber means that the mountings are subject to significantly smaller forces.